1. Field of the Disclosure
The present disclosure is directed to scintillators, particularly ruggedized scintillation detectors for industrial applications.
2. Description of the Related Art
Scintillation detectors have been employed in various industrial applications, such as the oil and gas industry for well logging. Typically, such detectors have scintillator crystals made of an activated sodium iodide material that is effective for detecting gamma rays. Generally, the scintillator crystals are enclosed in tubes or casings, which include a window permitting radiation induced scintillation light to pass out of the crystal package for measurement by a light-sensing device such as a photomultiplier tube. The photomultiplier tube converts the light photons emitted from the crystal into electrical pulses that are shaped and digitized by associated electronics that may be registered as counts and transmitted to analyzing equipment. In terms of well logging applications, the ability to detect gamma rays makes it possible to analyze rock strata as gamma rays are emitted from naturally occurring radioisotopes, typically of shales that surround hydrocarbon reservoirs.
Desired properties of scintillation detectors include high resolution, high brightness, and robust design to withstand mechanical and thermal loads, while providing a high quality hermetic seal to isolate the sensitive internals of the detector from harsh operating environments. In this latter aspect, a common practice in the utilization of scintillation detectors is to take measurements while drilling (MWD). For MWD applications, the detector should be ruggedized, that is, it should have a high shock resistance and be capable of withstanding high temperatures, while maintaining performance specifications for a reasonable lifetime.
Improved scintillation properties such as resolution and brightness have been achieved by the migration from conventional crystals such as alkali halides (e.g., sodium iodide), bismuth germinate (BGO), and gadolinium ortho-silicate (GSO) crystals, to rare-earth halides. However, successful integration of such materials has been found to pose numerous engineering challenges, including the development of suitable packaging and packaging techniques.
As such, there continues to be a need for improved scintillation detectors, particularly ruggedized scintillation detectors incorporating state of the art scintillator materials that can withstand the rigors of industrial applications.